Split antenna array rotatable on bearings mounted in split



March 9, 1965 A. R. SMITH ETAL SPLIT ANTENNA ARRAY ROTATABLE ON BEARINGS MOUNTED IN SPLIT Filed March 15, 1963 A. R. SM/TH INVENTORS ,4. H. WILLIAMSON JR BVW A TTORNEY United States Patent 3,173,144 SPLIT ANTENNA ARRAY ROTATABLE 0N BEARINGS MOUNTED IN SPLIT Arnold R. Smith, Chester, and Andrew H. Williamson,

.lr., Denville, NJ., assignors to Bell Telephone Laboratories, Incorporated, New York, N. a corporation of New York Filed Mar. 15, 1963, Ser. No. 265,418 4 Claims. (Cl. 343762) This invention relates to antenna systems and in particular to arrays of directional antennas.

Parabolic-reflector antennas have been widely used because they possess certain desirable electrical and mechanical features. They have, for example, relatively high gain characteristics and physical symmetries that are desirable from manufacturing and operating viewpoints. Unfortunately, however, they have far side lobe to main lobe sensitivity ratios which sometimes cause extraneous signals appearing within the far side lobes to produce undesirable effects. (The expression far side lobes, as used in this specification, is an expression of art meaning that the side lobes referred to subtend a relatively large angle with respect to the main or primary lobe.) The signals appearing in these side lobes are particularly objectionable when using recently developed low-noise highgain receivers to receive weak signals.

Antennas which have lower far side lobe to main lobe sensitivity ratios than those of parabolic-reflector antennas are horn-reflector antennas. Horn-reflector antennas also have low-loss feed lines and substantially uniform and highly efiicient transmission characteristics over relatively wide frequency and ambient temperature ranges. They have, therefore, been used to advantage with low-noise high-gain receivers to receive relatively weak signals. (Several types of horn-reflector antennas are disclosed in the literature. See, for example, US. Patent 2,416,675, issued to Beck and Friis on March 4, 1947; US. Patent 2,817,837, issued to Dale and Friis on December 24, 1957; and A Horn-Reflector Antenna for Space Communications by Crawford, Hogg and Hunt, beginning on page 1095 in the July 1961 issue of the Bell System Technical Journal.)

Although horn-reflector antennas have electrical characteristics which are superior in some applications to those of parabolic-reflector antennas, they have mechanical characteristics which result in more severe construction and operating requirements. They, for example, are larger than and lack the symmetry of comparable parabelie-reflector antennas. These two characteristics produce a number of undesirable results. Firstly, horn-reflector antennas require the use of stronger, which generally means heavier, structural elements. Secondly, the heavier structures in turn require larger and stronger mounting foundations. Thirdly, the heavier and larger structures have greater moments of inertia which require higher powered mechanical steering mechanisms. Fourthly, when radomes are required, the larger structures require larger radomes. Although these more severe construction and operating requirements have been successfully met in present day large horn-reflector antenna installations, they have resulted in large expenditures of time and money. It would, therefore, be advantageous to have antenna arrangements having mechanical characteristics similar to, or better, than those of parabolic-reflector antennas and electrical characteristics similar to those of horn-reflector antennas.

An antenna arrangement which includes this advantageous combination of characteristics, along with additional mechanical features, forms the principal subject matter of patent application Serial No. 265,386 filed on even date herewith by J. S. Cook and I. N. Hines. In one of its broader aspects, the Cook et a1. arrangement comprises a plurality of horn-reflector antennas arranged to form at least a portion of a substantially circular array with the apexes of the antennas at substantially the center of the array and the apertures of the antennas directed in substantially the same direction. The apexes are connected to an electrical coupler unit which in turn is connected to at least one transmission line. When used for receiving purposes, the coupler unit combines received signals for transmission over a transmission line to a receiver. On the other hand, when used for transmitting purposes, energy received from a transmitter is divided substantially equally between the horn-reflector antennas by the coupler units.

Although the invention disclosed in the previously mentioned Cook et al. application provides in an antenna installation an advantageous combination of electrical and mechanical characteristics, it would be desirable to further reduce the weight, moment of inertia and size of such an installation.

An object of the present invention is to further reduce the weight, moment of inertia and size of an antenna installation utilizing an antenna arrangement of the type forming the subject matter of the previously mentioned Cook et a1. patent application.

In accordance with the present invention in one of its broader aspects, a horn-reflector antenna arrangement embodying the Cook et al. invention is divided into two equal sections with the sections secured to respective sides of a vertical circularly shaped member, such as a ring member, so that the plane of the circular antenna array is substantially normal to that of the circular member. The center of gravity of the resulting structure is substantially over the center of a mounting base supporting the circular member. The circular member is rotatably supported by the mounting base so that the radiation pattern of the antennas may be changed in an elevational sense. The mounting base also permits the circular member and antennas to be rotated in a horizontal plane so that the radiation pattern of the antennas may be changed in an azimuthal sense.

The present invention provides several additional advantageous mechanical characteristics in antenna installations embodying the Cook et a1. invention. Firstly, because the resulting center of gravityof the combination of the horn-reflector antennas and circular member is substantially over the center of the mounting base, the moment arm of the structure is a minimum. Secondly, because the horn-reflector antennas are divided into two groups and secured to either side of the circular member, relatively lighter weight structural elements may be used in forming the antennas. Thirdly, the circular member has an inherent structural strength because of its continuous nature which permits lighter weight structural elements to be used to support the antenna arrangement on the mounting base. Fourthly, the overall installation is more compact. These characteristics in turn permit the overall weight of the structure to be reduced, thus reducing the supporting requirements of the mounting base. Furthermore, providing a minimum moment arm and reducing the overall weight reduces the moment of inertia which in turn reduces the requirements on the mechanical driving means. In addition, the more compact nature of the overall installation permits a smaller radome to be used when a radome is required.

Other objects and features of the invention will become apparent from a study of the following detailed description of a specific illustrated embodiment.

In the drawings:

FIGS. 1 and 2 are two views of an embodiment of the invention.

The embodiment of FIGS. 1 and 2 includes a first group 3 of horn-reflector antennas through 13 and a second o p f h r -refle tor antennas 1.4 hrough. 17,. The. antennas are aflixed to a hub member 18 to form a substantially circular array with the antenna apexes at substantially the center of the array, the antenna apertures directed in substantially the same direction and the groups displaced to respective. sides of a' diamet eti of the array. Hub member 18: is'i n turn" affixed to a vertical ring member. Ring member. 19 is supported in a vertical position by 't p rha mem a: 1 Par i hh h ere- 19 is supported in upper base member 20. by roller bearin gs mountedin uppler base'rneniber ztifat points 21 22, and 23 so that the radiation anteater antennaarra y may be changed inan elevational sense l i Upper base member is rotatably mounted on a lower. base member: 24 so the, radiation pattern of the antenna array may be changed in an azimuthal sense; w The antenna array and its supporting structure are enclosed by a radome 2 5. Radome 25 securedfat its base to acyli ndric ally shaped wall 26. l i A' 'i Drive mechanisms; enclosed within base members 2t). and 24; are used for rotating ring withres pectto upper base member 20 and upper basememberZQ with respect to loyver base member 2.4 In aecorclancefvvith a feature of the invention, the r elativelydovv momentot inertia and the well balanced natures of embodiments of h n nt n Perm h 'ehvsmhe i sh i vjeh inexpenisve friction type of coupling tinsteadof gear e t u l ng). to h u ed h e driving hrshehh Th mbo ime h w h IGS- and 2 s i s r ted in a fixed site application. Embodiments also lend; themlves dv tage l 9. m e ev lis ti e The l Y Y light we h o hahh eht whi es ew p m m t h t a ar d; ea il n ni i s? w e ion w h a min m Q trrt s st l s h v t se i i n r ha a r ed b he tt hsnut hers i -j Al hou h nl n smh -dhhth at h hvsht sn h e n llu tra and dsss hsd eta l; t s t ust te d h t he enhhs lmsht may h de i e ss k l n h r w thqht d ra t h he e rh eh t o e f he hvt t h- What sc imed 1. A m unt for. a p u a i y of h9 lfi QI.- an e na said mount comprising a circularly. shaped member, means located at least at three places on the periphery of said circularly shapedmember and, rotatably. sup porting said circ'ularly shapedmember in a vertical plane, means securing one-half of said antennas to one side of said circularly shaped member and the other half of a an enn o he O h i if i s f h ht shaped member with said antennas forming atleast a portion of a substantially circular array with their apexes directed towards the center of the array, their apertures directed in substantially the same direction, the plane of said array substantially normal to that of said ci r c :ularly shaped member and the combined en of ty of aid nt nna n ai QiW lhtshaped member substantially directly above the center 01; said supporting means, and

mechanical driving means eonneeted bet-ween said circularly shaped member and said means rotatably supporting said circularly shaped member to change the rotational position of said circularly shapedmemher.

2. A mount in accordance with claim 1 in which said circularly shaped member comprises a ring member.

3. A mount for aplurality of horn-reflector antennas, said mount comprising i a base member having at least three sets of bearings for receiving and supporting at its periphery a circularly shaped member in a vertical plane,

a circularly shaped member. supported in a vertical plane by said base member bearings,

means securing a group of one-halt of said antennas to one, side of said circularly shaped member and the remaining antennas to the other side of said circularly shaped member with said antennas forming atleast a portionof a substantially circular array with the apexes of said antennas at substantially the center of said array, the apertures of said antennas directed in substantially the same direction, the plane of said array substantially normal to that of said circularly shaped member and the combined center of gravity of. said antennas and said circularly shaped member substantially a ie tly above the center of said supr g m a con e d be e s i i cularly shaped member and said base member to change the rotational position of said circularly shaped member. V

4 A mount in accordance with claim 3 in which said circularly shaped member comprises a ring member.

References Cited. in the file of this patent UNITED STATES PATENTS 2,426,183 Deloraine et al Aug. 26, 19.47 2,480,829 Barrow etal Sept. 6, 1949 2,530,890 Mattke Nov. 21, 1950 2,814,038 Miller a Nov. 19, 1957' 

1. A MOUNT FOR A PLURALITY OF HORN-REFLECTOR ANTENNAS, SAID MOUNT COMPRISING A CIRCULARLY SHAPED MEMBER, MEANS LOCATED AT LEAST AT THREE PLACES ON THE PERIPHERY OF SAID CIRCULARLY SHAPED MEMBER AND ROTATABLY SUPPORTING SAID CIRCULARLY SHAPED MEMBER IN A VERTICAL PLANE, MEANS SECURING ONE-HALF OF SAID ANTENNAS TO ONE SIDE OF SAID CIRCULARLY SHAPED MEMBER AND THE OTHER HALF OF SAID ANTENNAS TO THE OTHER SIDE OF SAID CIRCULARLY SHAPED MEMBER WITH SAID ANTENNAS FORMING AT LEAST A PORTION OF A SUBSTANTIALLY CIRCULAR ARRAY WITH THEIR APEXES DIRECTED TOWARDS THE CENTER OF THE ARRAY WITH THEIR APERTURE DIRECTED IN SUBSTANTIALLY THE SAME DIRECTION, THE PLANE OF SAID ARRAY SUBSTANTIALLY NORMAL TO THAT OF SAID CIRCULARLY SHAPED MEMBER AND THE COMBINED CENTER OF GRAVITY OF SAID ANTENNAS AND SAID CIRCULARLY SHAPED MEMBER SUBSTANTIALLY DIRECTLY ABOVE THE CENTER OF SAID SUPPORTING MEANS, AND MECHANICAL DRIVING MEANS CONNECTED BETWEEN SAID CIRCULARLY SHAPED MEMBER AND SAID MEANS ROTATABLY SUPPORTING SAID CIRCULARLY SHAPED MEMBER TO CHANGE THE ROTATIONAL POSITION OF SAID CIRCULARLY SHAPED MEMBER. 